Fuel systems for motor vehicles are known to include a fuel tank and a filler tube through which fuel is dispensed into the tank. It is known to use a removable cap at the end of the filler tube to close the tube. The threaded fuel cap is the primary seal for the fuel system on most domestic vehicles. For the threaded cap to seal the fuel system properly, the cap must be twisted on correctly. If a fuel cap is not properly tightened, is missing or is defective, a significant amount of fuel can be released to the atmosphere through evaporation from the fuel tank.
It is known to use a movable damper and a rubber seal to close the fuel system, either as the primary shut-off valve or as a secondary, supplemental shut-off. A known assembly of this type includes a metal tube or sleeve and a plastic insert or cover adapted to be received within the sleeve. An annular groove is provided on the outer surface of the plastic insert, and a rubber seal or the like is positioned within the groove between the inner surface of the metal sleeve and the outer surface of the plastic insert. Properly functioning, an assembly of this type can be effective in minimizing the loss of fuel from the fuel system. However, through age, fatigue and deterioration of the seal and associated components, the sealed area between the insert and the outer sleeve provides a path for the leakage of vapors from the tank. Even a small leak can result in significant loss of fuel and environmental pollution.
It also is known to use a positive sealing insert in the end of the filler tube and a capless refueling closure unit at the end of the filler tube. Known capless refueling systems are complex and costly. Assembly of such a system is difficult and time consuming. Disassembly for repair, integrity or crash worthiness and overall sealing effectiveness have not achieved acceptability in many such systems.
Vehicle crash worthiness standards require that the fuel system structural integrity remain in the event of a crash. This includes integrity of the tank, the filler tube and a closure therefore, so that fuel does not leak and create a fire danger. This can present challenges in attaching end closure assemblies since the fuel tank is often connected to the vehicle frame and the filler tube extends through or near to outer fender bodies that may be significantly damaged during a crash. A closure for the filler tube, and thus a closure for the fuel tank, must maintain its integrity and effectiveness even if outer portions of the filler tube are damaged extensively along with the body panels through which the tube extends.
What is needed in the art is a vehicle fuel system filler assembly that includes an effective shut-off valve assembly with reduced area of potential leakage together with an outer closure therefore that can be assembled quickly and easily, yet separates for crash worthiness or needed repairs.